microPlatform update 0.17


Zephyr microPlatform changes for 0.17

Zephyr heading towards end of v1.12 development cycle, MCUboot heading towards 1.2.0 release, samples compatibility updates.

Linux microPlatform changes for 0.17

No changes have gone into the LMP since 0.16.

Zephyr microPlatform


Zephyr heading towards end of v1.12 development cycle, MCUboot heading towards 1.2.0 release, samples compatibility updates.


  • MCUboot's configuration system overhauled
  • Zephyr with Spectre v2 mitigations, build system improvements, LED API, scheduler re-vamp, USB improvements
  • Reference sample compatibility updates for upstream LED GPIO changes




Configuration system overhaul:
  • The bootloader's configuration system was generalized across its ports into a single mcuboot_config/mcuboot_config.h abstraction. Documentation on how to specify this configuration file was added to the porting guide (doc/PORTING.md).


Mynewt unit tests:
  • The unit tests on the Mynewt target were fixed.



Retpolines on x86:
  • x86 CPUs affected by Spectre v2 now support retpolines when invoking interrupt and exception handlers, during thread entry, and when invoking syscall handlers.

These changes also saw the removal of the (unused) _far_jump() and _far_call() routines.

LED and Button Definition Moves:
  • This continues the long-term project to move device configuration from Kconfig to Device Tree.

LED and button definitions were removed from all STM32 board.h files, since the corresponding defines now come from device tree. This is a breaking change, as the old XXX_GPIO_PORT is now XXX_GPIO_CONTROLLER. Applications which used the old names will need updates.

NXP Kinetis SoCs were also converted to generate this information from Device Tree. This change preserved names, but did not include updates for the FXOS8700 or FXAS21002 temperature sensors or the MCR20A 802.15.4 radio. Rather than break these sensors, this update has reverted the NXP-specific conversion patches until functionality is restored upstream.

Deprecated __stack macro removed:
  • The __stack macro, which was deprecated in favor of K_STACK_DEFINE before v1.11 was released, has been removed.
mbedTLS update to fix remote execution holes:
  • The mbedTLS cryptography library was updated from version 2.7.0 to version 2.8.0, addressing CVEs 2018-0488 and 2018-0487. These are remote execution vulnerabilities that could occur when TLS or DTLS is in use.
k_thread_cancel() deprecated:
  • The k_thread_cancel() API is deprecated. Applications should use k_thread_abort().
Generic storage partition rename:
  • The NFFS flash partition available on many boards, which was previously aliased to nffs_partition, has been renamed to storage_partition, to reflect its general usefulness for a variety of storage systems. Its existence is now controlled via a CONFIG_FS_FLASH_MAP_STORAGE.

Out of tree applications using the old alias or configuration option to access this partition will need updates.

  • The ARC architecture now supports CONFIG_STACK_SENTINEL, which can help diagnose stack overflow issues.

SEGGER RTT support is now enabled on all NXP MCUs.

Support was added for Cadence's proprietary XCC compiler toolchain for the XTensa architecture, along with support for the intel_s1000 SoC. Judging from these drivers, the SoC is intended for use in speech and other audio processing. Zephyr SoC-level support is provided for DMA, I2S, UART, GPIO, USB, and I2C, with board support via intel_s1000_crb.

  • I2C driver support was enabled for all the official nRF5 boards provided by Nordic Semiconductor.

The bbc_microbit now supports flash partitions for mcuboot and on-chip storage.

Build system:
  • A variety of improvements were merged into the build system.

Notably, the build system now caches information obtained from the toolchain, optimizing subsequent invocations of cmake using the same toolchain. Factor of two speedups have been observed when the cache is used. A few problems have been identified and fixed up since the initial merge, but hopefully the major issues are resolved.

In another significant addition, the build system now contains an initial Python-based menuconfig alternative. This can currently be used by running "ninja pymenuconfig" on all supported targets (though Windows users will need to install an additional wheel). This is a significant improvement for Windows users, who previously have not had a configuration system browser. The pymenuconfig target is experimental. When it reaches sufficient feature parity with the existing menuconfig target, it will replace it, and the C-based Kconfig tools will be removed from Zephyr.

Further improvements include better error feedback when toolchains are not found, the list of printed boards now respecting BOARD_ROOT, and silencing of verbose compiler check messages.

  • There is a new API for LEDs in include/led.h. (Zephyr had an API for strips of LEDs; this new API is for controlling individual lights.) The initial API includes support for basic on/off, as well as brightness and blinking. A driver and sample application for the TI LP3943 LED controller were also merged.

The ST LSM6DSL inertial module driver saw a cleanup and now supports sensor hub mode. This allows the LSM6DSL to act as a sensor hub by connecting additional I2C slave devices through to the driver via the main communication channel.

STM32L0 and L4 microcontrollers now support the MSI (multi-speed internal) clock as a system clock source.

The uart_pipe console driver now supports both edge and level triggering, allowing it to work with CDC ACM.

The MCUX GPIO driver now uses device tree.

A GPIO driver for NXP i.MX SoCs was merged.

Device Tree:
  • Bindings were added for the DesignWare CAVS multilevel interrupt controller.

GPIO nodes are now present on all Kinetis SoCs.

  • The search results pages for the online Zephyr documentation now have much cleaner output.

Zephyr's documentation describing its Kconfig usage was re-worked and improved as part of the transition towards a Python-based menuconfig alternative.

  • The kernel's scheduler interface was significantly refactored and cleaned up. The scheduler's system interface was decreased to twelve functions; notably, usage of _Swap() was removed in various places in favor of a new _reschedule().

Userspace configurations now support dynamic creation of kernel objects. Previously, kernel objects (such as mutexes, pipes, and timers) needed to be declared statically. This is because a special linker pass is used when building the Zephyr image, which creates a perfect hash table which was used to validate if a memory address passed from userspace pointed to a valid kernel object, among other security checks. In addition to this hash table, Zephyr now supports maintaining metadata for dynamically created kernel objects using the new red/black tree implementation that was added in the v1.12 development cycle. Dynamic kernel objects are allocated and freed from the system heap. The new allocate and free routines are respectively k_object_alloc() and k_object_free(). They are currently only callable from supervisor mode.

  • The singly-linked list implementation in include/misc/slist.h is now implemented in terms of a new macro metaprogramming header, include/misc/list_gen.h. This new header allows generation of static inline routines implementing "list-like" behavior (i.e. defining operations for getting, removing, inserting, etc.) for any compound data type that implements a base set of operations. The base operations from which the others are derived are: initialization; getting the "next" node; setting the next, head, and tail nodes; and peeking at the head and tail nodes.

The JSON library's internal descriptor type is more tightly packed, using bitfields to place information formerly found in four integers into 32 bits worth of bitfields. This results in a net savings of read-only data at a slight increase in text size.

  • A sample application demonstrating the BLE broadcaster role by providing Apple iBeacon functionality was added in samples/bluetooth/ibeacon.

Samples using LEDs and buttons were updated following the device tree name change from PORT to CONTROLLER described above.

The LWM2M sample was re-worked to add configuration overlay fragments for enabling Bluetooth networking and DTLS. The README was updated with new instructions for building the sample.

  • The effort to prepare Zephyr's tests for inclusion in a test management system continues.

Various tests were cleaned up with style, tag, and category fixes, along with numerous tests receiving Doxygen-based documentation.

The sanitycheck script now parses test cases declared by a test suite from the source code, using regular expressions.

Sanitycheck also now supports a --list-tests flag, which prints declared test cases. Its output can be further refined by passing the -T option a relative path to a subdirectory of "tests" (e.g. -T tests/net/socket).

The test suite core now includes support for skipping tests when they are not supported.

  • There was a fair bit of USB-related activity which spanned areas in the tree.

The USB DFU class driver was heavily re-worked and moved to subsys/usb/class. The driver now determines the flash partition layout for the currently running image and an area to store an update image via device tree flash partitions, matching Zephyr's MCUboot area support mechanism. This allows Zephyr applications to add firmware update support by enabling the USB DFU driver and booting under MCUboot. Refer to the README and other documentation in samples/subsys/usb/dfu for more details.

The hci_usb sample application, which allows a Zephyr device which supports USB and a Bluetooth controller to act as a Bluetooth dongle, had its core USB operations generalized and migrated into the core USB subsystem. The sample application is now much smaller; what remains essentially just enables the driver.

The wpanusb sample, which allows Zephyr applications to expose 802.15.4 radio functionality to a host via USB, saw a major cleanup. This sample will be more widely useful upon release of corresponding Linux drivers.


Networking fixes:
  • There were several networking-related bug fixes: a fragment double-free, a build error for HTTP clients, a buffer overflow in the hostname storage area, an ARP null network packet dereference, and a miscalculation of ICMPv6 packet payload length and checksum fields.
pthread_cond_signal on cooperative threads:
  • Calling pthread_cond_signal() from a cooperative thread no longer yields.
SMP fixes for irq_lock() shim:
  • The irq_lock() compatibility layer on SMP configurations was fixed, avoiding potential deadlocks when swapping away from a thread that holds the lock.
Kernel priority validation:
  • The kernel scheduler's validation of priority levels was fixed.
Driver capability check:
  • A bug which allowed user mode code to force the kernel to execute code at address 0x0 has been fixed by introducing an extra validation step at every syscall entry point.
I2C user buffer copy fix:
  • A race condition which could potentially allow user space code to modify memory containing I2C messages before the kernel-level handler runs was closed.
ARC threading fixes:
  • Issues preventing successful thread context switch during exception return on ARC were fixed. The fatal error handler on that architecture also no longer hangs the system after aborting a non-essential thread.
BusFault fixes on ARMv8-M:
  • The BusFault Status Register bits on ARMv8-M MCUs are now properly cleared when that fault occurs.
Bluetooth Mesh fixes:
  • The Bluetooth Mesh implementation continues to become more robust, with three bug fixes affecting initialization vectors and node identity advertising, and two other cleanups.
Boot banner fixed for out of tree applications:
  • The boot banner now correctly prints the Zephyr "git describe" output when the application is outside the Zephyr tree.
Device tree compiler warning fixes:
  • A variety of warnings emitted when using dtc version 1.4.6 are now fixed. These fixes appear to be backwards-compatible.
USB fixes:
  • A variety of USB-related bug fixes went in, including a fix for the DesignWare driver's excessive generation of zero-length packets, a missing byte order conversion computation in the common configuration descriptor, and other fixes and cleanups.
LSM6DSL build fix:
  • The ST LSM6DSL inertial module driver was converted to use the new SPI API, following the removal of the old API.

hawkBit and MQTT sample application


LED GPIO controller portability check:
  • The sample now checks for old-style (LED_GPIO_PORT) and new-style (LED_GPIO_CONTROLLER) device names when finding the GPIO device controlling the user LED.


  • Not addressed in this update

LWM2M sample application


LED GPIO controller portability check:
  • The sample now checks for old-style (LED_GPIO_PORT) and new-style (LED_GPIO_CONTROLLER) device names when finding the GPIO device controlling the user LED.


  • Not addressed in this update

Linux microPlatform


No changes have gone into the LMP since 0.16.


  • No changes have gone into the LMP since 0.16.


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